Step 1: Prepare the eggplant. Lay eggplant slices in a single layer on paper towels. Sprinkle generously with salt and let sit for 20-30 minutes to draw out moisture. Pat thoroughly dry with paper towels.
Step 2: Season and grill eggplant. In a small bowl, whisk together 2 tbsp olive oil, chopped rosemary, 1 tsp salt, and 1/2 tsp black pepper. Brush both sides of the dried eggplant slices with the rosemary oil. Preheat your grill or grill pan to medium-high heat. Grill eggplant slices for 3-4 minutes per side, or until tender and nicely charred with grill marks. Transfer to a plate and let cool slightly.
Step 3: Make the filling. In a medium bowl, combine ricotta cheese, Parmesan cheese, chopped spinach, chopped sun-dried tomatoes, minced garlic, and red pepper flakes (if using). Mix well until all ingredients are evenly distributed. Taste and adjust seasoning if needed.
Step 4: Assemble the rolls. Lay a grilled eggplant slice flat. Place about 1-2 tablespoons of the ricotta filling at one end. Carefully roll up the eggplant slice to enclose the filling. Repeat with the remaining eggplant slices and filling.
Step 5: Serve. Arrange the rosemary-infused grilled eggplant rolls on a platter. Serve warm or at room temperature. Optionally, drizzle with balsamic glaze or a light tomato sauce, and garnish with fresh rosemary sprigs or chopped parsley.